"Despite decades of research, a number of questions remain in our
understanding of the physical processes involved in
superconductivity," Wiebe said.

FSU News

FSU researcher unlocking secrets of superconductivity

by Amy Winters

Recent experiments led by a Florida State University researcher
provide a major step toward solving a two-decades-old
materials-science mystery—and are shedding light on the mysteries
of superconductivity.

Christopher Wiebe

Christopher Wiebe, an assistant professor of physics at FSU, and
colleagues from the United States and Canada report that their
research has made important progress toward the ultimate goal of
creating new materials that are optimized for their magnetic and
electrical properties. A paper describing their work is published in
the online edition of the prestigious science journal Nature
Physics; it can be accessed at www.nature.com/.

For nearly a century, scientists have known that many metals become
"superconductors"— meaning they lose all electrical resistance and
can conduct electric current endlessly—when exposed to very low
temperatures. The application of this knowledge has led to such
technological innovations as magnetic-levitation trains and magnetic
resonance imaging, or MRI.

"Despite decades of research, a number of questions remain in our
understanding of the physical processes involved in
superconductivity," Wiebe said. "Our experiments provided rare
glimpses into the complicated dance of electrons at very low
temperatures. Hopefully these experiments will answer some of those
questions and lead to even greater technological leaps."

A quest for understanding of the physical processes involved in
superconductivity— specifically the behavior of electron pairs—has driven more than 20 years of condensed-matter physics research,
because such knowledge could lead to the development of
revolutionary technological devices.

In the project Wiebe participated in, an international team of
researchers combined their efforts to find out what happens to
electrons when cooled in a material known as URu2Si2, a
uranium-based compound with superconductive properties. The
properties of the compound were determined at FSU's National High
Magnetic Field Laboratory. Wiebe, FSU graduate student John Janik
and their colleagues were able to pinpoint why certain anomalies
were seen in property measurements by scattering neutrons using a
state-of-the-art instrument called a Disk-Chopper Spectrometer,
housed at the National Institute of Standards and Technology (NIST)
in Gaithersburg, Md. The Disk-Chopper shoots a controlled beam of
cold neutrons, generated by a nuclear reactor, at the URu2Si2 sample.

At roughly 256 degrees below zero Celsius, the once-nomadic
electrons that had roamed freely about the compound's atomic
structure—and generated their own magnetic fields—behave in a
more orderly and cooperative fashion. Physicists don't know how or
why this occurs. While the research in the Nature Physics paper does
not answer those questions, it does offer important clues about the
behavior of electrons. It also rules out many of the theories for
the behavior presented so far, inching science toward an answer.

"Neutrons are remarkable probes of phenomena within solids," Wiebe
said. "This work could not be possible without the support of the
NIST and the collaboration with other national laboratories such as
the magnet lab."

The National Science Foundation funds user programs at both the
magnet lab and the Center for High Resolution Neutron Scattering at
the NIST.

In addition to FSU, the magnet lab and the NIST, other participants
in this research came from McMaster University in Hamilton, Ontario,
Canada.

The National High Magnetic Field Laboratory develops and operates
state-of-the-art, high-magnetic-field facilities that faculty and
visiting scientists and engineers use for research. The laboratory
is sponsored by the National Science Foundation and the state of
Florida. To learn more, visit www.magnet.fsu.edu.